This 1/4" thick phenolic riser kit for the Holley 2300 carb that is machined specifically for the 1967-69 Corvette. The gaskets will need to be trimmed to fit perfectly, it is as easy as trace and cut with a scissors. Add a little performance to your machine the cheap way, and keep the heat away from the carburetor to solve the heat soak or carburetor boiling issues. This kit will do all three carburetors with the correct length for the studs. Why waste time fooling around with threaded rod? Do it right the first time.